1. Field of the Invention
The present invention relates to a chucking member, and a chucking device and a charged particle beam apparatus using the chucking member.
2. Description of the Related Art
In a manufacturing process of a semiconductor element, a sample (target) such as a semiconductor wafer made of silicon is sucked on and held on a chucking stage of a semiconductor manufacturing apparatus or a semiconductor inspection apparatus. Holding the target on the chucking stage is necessary for, for example, a step of polishing the target to obtain a mirror surface, a step of exposing part of a photosensitive member that is called resist and that is formed on the target with light or an electron beam, a step of removing the resist which has been exposed with the light or beam, and a step of inspecting the target. The chucking stage that holds the target is surrounded by gas such as the atmosphere, nitrogen, or oxygen. The pressure of the gas ranges from about 1×105 Pa, which is the atmospheric pressure, to about 1×10−7 Pa, which is high vacuum. For example, Japanese Unexamined Patent Application Publication No. 9-283605 describes a configuration in which a chucking stage attracts and holds a target while a plurality of very small protrusions support the target.
Wiring of a semiconductor wafer is becoming finer and the area of the semiconductor wafer is becoming larger. In recent years, a large-size wafer with an outer diameter of 200 or 300 mm is mainly used.
Meanwhile, in recent years, a manufacturing apparatus similar to an apparatus for manufacturing a semiconductor element is employed for manufacturing an optical disc or a substrate for an LED by using a semiconductor laser. The material of the wafer for manufacturing the substrate is selected from, for example, compound semiconductors of GaN and InGaN, sapphire, and SiC. The wafer for such a purpose of use may occasionally have an outer diameter of about 100 mm that is smaller than the outer diameter of the semiconductor wafer.
Many manufacturing steps including, for example, an exposure step are common between the case in which the semiconductor element is manufactured and the case in which the optical disc or the substrate for the LED is manufactured. If the same semiconductor manufacturing apparatus can be used for the large semiconductor wafer and the relatively small wafer for the optical disc or the substrate for the LED, it is not necessary to introduce different semiconductor manufacturing apparatuses or to modify a semiconductor manufacturing apparatus to meet the purpose of use, and thus the manufacturing cost can be decreased. Owing to this, a chucking stage that can hold targets with different sizes is desired.
An chucking stage typically has a plurality of vacuum holes in accordance with the size of a target that is expected to be attracted (a region of the chucking stage with the vacuum holes is also called “vacuum hole formation region”). If a target having a size smaller than the expected size is mounted on the chucking stage, part of the vacuum holes is not covered with the target and is exposed. Then, when the target is attracted, outside air may be vacuumed through the exposed vacuum holes. In this case, it is difficult to stably attract and hold the target.
Therefore, it is desirable to stably hold the target having the size smaller than the vacuum hole formation region of the chucking stage.